You repaint the ceiling, and weeks later the brown stain is back. That’s because paint only hides the problem — water from the unit above is still seeping through the concrete. Here’s how PU injection seals it at the source, what it costs, and who is responsible under Malaysian strata law.
General information for Klang Valley homeowners — not legal advice. Send us a photo of your ceiling on WhatsApp for a fast answer.
In a condo, apartment or flat, your bathroom ceiling is the underside of your upstairs neighbour’s bathroom floor. When the waterproofing membrane in their floor fails — or water escapes around their floor trap, shower area or pipe penetrations — water soaks into the concrete slab and slowly tracks down until it appears as a stain, damp patch or drip on your ceiling. Malaysians call this inter-floor leakage (“air bocor dari unit atas”).
Common sources from the unit above include failed bathroom waterproofing, a leaking floor trap or long-neglected silicone, water pooling from a poorly graded floor, or (less commonly) a genuine pipe leak. Because the water travels sideways through the concrete before it drips, the wet spot on your ceiling is often not directly under the actual source — which is why guessing and patching rarely works. For a broader look at causes and repair options, see our ceiling leak repair guide → and inter-floor leakage guide →.
The most common mistake is to scrape, skim and repaint the stained ceiling. It looks perfect… for a few weeks. Then the brown stain bleeds back through, the new paint bubbles, and you’re back to square one — because the water was never stopped. Paint (and even “waterproof” ceiling paint) sits on the underside of the slab; the water is coming from above it. You’re treating the symptom while the concrete stays wet.
To actually fix it, you have to stop water entering or passing through the slab. That means either re-waterproofing the floor above, or sealing the slab from within — which is what PU injection does.
PU injection (polyurethane injection grouting) seals a leaking concrete slab from the inside:
Crucially, it’s done from your side (the lower unit’s ceiling) — so you don’t need to hack up your neighbour’s bathroom floor, and you don’t have to wait for them to act.
| Method | What’s involved | Mess / disruption | Best for |
|---|---|---|---|
| PU injection | Drill & inject resin into the slab from below | Low — no hacking, done from your unit | Slab seepage & inter-floor bathroom leaks |
| Re-waterproofing (hack & re-screed) | Hack the floor above, relay membrane, re-tile | High — needs access & use of the upstairs unit | Failed floor waterproofing (permanent fix at source) |
| Cementitious coating | Rigid waterproof coating on a surface | Medium | Exposed surfaces, not cracks that move |
| Repaint / skim only | Cosmetic cover on the ceiling underside | Low | Nothing — the leak comes back |
PU injection is popular precisely because it avoids the biggest headache of the “proper” fix — getting into the upstairs unit and tearing up their floor.
PU injection is highly effective for the most common cause: water seeping through the concrete slab and around floor traps. Done properly it seals the path and stops the leak, and the flexible resin tolerates minor structural movement.
The honest caveat: PU injection seals concrete seepage — it does not repair a burst or broken water pipe buried in or above the slab. If the real source is a damaged pressurised pipe, that’s a plumbing repair, not a waterproofing job. This is why we always try to identify the true source first: if we believe it’s a pipe, we’ll tell you honestly rather than inject over it.
Most waterproofing contractors price PU injection per injection point — commonly around RM80–RM250 per point in the Klang Valley — so a ceiling that needs several points can add up unpredictably, and you often don’t know the final bill until they’re done.
| Typical KV market | ClickBina | |
|---|---|---|
| Pricing basis | Per injection point | Flat fee per bathroom ceiling |
| Indicative cost | ~RM80–RM250 / point | RM450 flat |
| Surprise charges | Common (more points = more cost) | None — you know the price up front |
| Warranty | Varies | 6-month no-leak warranty |
This is where these leaks get stuck for months. Under the Strata Management Act 2013 (Section 142), if a leak appears on your ceiling, the defect is legally presumed to come from the parcel (unit) directly above yours — unless proven otherwise. It’s a starting point, not an automatic verdict: an inspection can show the cause is actually common property or something else.
The official process runs through your building management (JMB/MC), not directly between neighbours. In brief: you report the leak, management is meant to inspect (within about 7 days) and issue a Form 28 Certificate of Inspection (within about 5 days) identifying the cause and who’s responsible; unresolved disputes escalate to the Commissioner of Buildings (COB) and then the Strata Management Tribunal.
In practice this can drag on for months while your ceiling keeps rotting — which is why many owners choose to stop the damage from their own side now with PU injection, and pursue the responsibility/cost question with management in parallel. (For your rights and the management’s duties, see our strata rules guide →.)
This is general information, not legal advice. Responsibility in any specific case is decided by the management’s inspection under the Strata Management Act 2013.
ClickBina is a Klang Valley home-services and waterproofing contractor. Send us a photo of your leaking ceiling on WhatsApp and tell us your area — we’ll give you a fast, honest read on whether PU injection is the right fix, and a flat RM450 price with a 6-month warranty. If we think it’s a pipe or needs work upstairs, we’ll say so.
Tell us what you need — we reply within the hour.